Hydrocracking process

ABSTRACT

A HYDROCRACKING PROCESS FOR INCREASING THE YIELD OF LOWER BOILING HYDROCARBONS FROM HEAVY HYDROCARBON FRACTIONS BY OXIDIZING THE HEAVY HYDROCARBON AND CONTACTING SAID, OXIDIZED HEAVY HYDROCARBON FRACTION WITH HYDROGEN IN THE PRESENCE OF AN AROMATIC POLYCARBOXYLIC ACID OR ANHYDRIDE PRODUCING COMPOUND.

United States Patent 3,591,486 HYDROCRACKENG PROCES Reese A. Peck and Raymond F. Wilson, Fishlnll, N.Y., assignors to Texaco Inc., New York, N.Y. N0 Drawing. Filed Dec. 27, 1968, Ser. No. 787,561

Int. Cl. C07c 27/10; (310g 13/00 US. Cl. 208-85 Claims ABSTRACT OF THE DISCLOSURE A hydrocracking process for increasing the yield of lower boiling hydrocarbons from heavy hydrocarbon fractions by oxidizing the heavy hydrocarbon and contacting said oxidized heavy hydrocarbon fraction with hydrogen in the presence of an aromatic polycarboxylic acid or anhydride producing compound.

This invention relates to a hydrocracking process for increasing the yield of lower boiling hydrocarbons and more particularly to a hydrocracking process wherein an oxidized heavy hydrocarbon fraction charge stock is contacted with hydrogen in the presence of an aromatic polycarboxylic acid or anhydride producing compound.

Generally, hydrocracking finds its highest degree of utility in the cracking of hydrocarbons boiling in the heavy naphtha and light gas oil range. It has however met with only limited acceptance in the upgrading of heavy hydrocarbon oils, particularly those containing high boiling components having substantial sulfur and nitrogen contents such as total crude oil, topped crudes and residua, shale oil, coal tars, etc. The various sulfur and nitrogen compounds present in such oils tend to poison the hydrocracking catalyst and to deposit coke during catalytic hydrocracking operation, whereas in thermal hydrocracking processes the yields of lower boiling hydrocarbons are small in comparison to processes utilizing a catalyst. It has been particularly found that the higher boiling petroleum fractions of such oils, i.e. those fractions boiling above about 750 F., and particularly above about 850 F., contain relatively high proportions of the abovementioned objectionable contaminating materials. Accordingly, conventional hydrocracking of such fractions, or of oil feeds containing such fractions, has proved to be of very limited effectiveness.

It will be appreciated, therefore, that there is presently a high incentive for discovering a successful means for hydrocracking heavy hydrocarbon oil feeds containing high boiling petroleum fractions to valuable lower boiling products.

It is therefore an object of this invention to 'provide an improved process for hydrocracking such feeds whereby higher yields of lower boiling hydrocarbons are obtained.

It has now been found that lower boiling hydrocarbons can be obtained from heavy hydrocarbon fractions through the use of a process which comprises oxidizing a heavy hydrocarbon fraction with an oxidant optionally in the presence of an oxidation promoting catalyst and-contacting said oxidized heavy hydrocarbon fraction with hydrogen in the presence of a promoting amount of an aromatic polycarboxylic acid and/or anhydride producing compound for a time suificient under hydrogen contact conditions to increase the proportion of lower boiling hydrocarbons than that present in the original heavy hydrocarbon charge stock. Thus it has been discovered that the combination of an oxidation step plus hydrogen contact step in the presence of an aromatic polycarboxylic acid or anhydride, producing compound (hereinafter referred to as aromatic polycarboxylic compound) produces a yield of lower boiling hydrocarbons significantly greater than the yield of lower boiling hydrocarbons that is ob tained utilizing either the thermal hydrogen treatment alone in the absence of an aromatic polycarboxylic compound promotor or the combination of oxidation step plus hydrogen contact in the absence of aromatic polycarboxylic compound.

In general the process of this invention is carried out by first contacting the heavy hydrocarbon fraction with an oxidizing amount of an oxidant optionally in the presence of an oxidation promotion catalyst for a time sufiicient to effect oxidation of at least a part of the heavy hydrocarbon fraction. The heavy hydrocarbon fraction that has been oxidized, is then contacted with hydrogen in the presence of a promoting amount of an aromatic polycarboxylic compound, a promoting amount being that concentration by weight which during the hydrogen contact step produces a yield of lower boiling hydrocarbon greater than the yield of lower boiling hydrocarbons obtained in the absence of an aromatic polycarboxylic compound. In general a concentration of aromatic polycarboxylic compound from about 0.1 percent to about 5 percent, more preferably from about 0.5 wt. percent to about 2 wt. percent based upon the weight of the heavy hydrocarbon charge stock is utilized during the hydrogen contact step. The lower boiling hydrocarbon fractions are then recovered from the charge stock by conventional means, such as by distillation or vacuum stripping optionally using an inert stripping gas. As stated above, the oxidation step provides for the oxidation of at least a part of the heavy hydrocarbon fraction. By the use of the term at least a part it is meant that the combined oxidation and hydrogen contact steps produces lower boiling hydrocarbons greater than that obtained in the absence of an aromatic polycarboxylic compound. Thus, the oxidation step preferably produces increases in oxygen content of the heavy hydrocarbon charge stock of from about 0.1 wt. percent to about 10.0 wt. percent more preferably from about 0.25 wt. percent to about 5.0 wt. percent.

The type of oxidant, the concentration of oxidant, the presence or absence of an oxidation promoting catalyst (hereinafter referred to as catalyst), and the temperature and pressure during the oxidation step can be varied over a wide range, the particular conditions being those which produce oxidation of at least a part of the heavy hydrocarbon fraction. In addition the conditions for hydrogen contact step can be varied over a wide range as to liquid hourly space velocity (LHSV, volume of feed to volume of contactor per hour), volume of hydrogen to volume of heavy hydrocarbon fractions (s.c.f., standard cubic feet/bbl.), temperature, pressure and the concentration of aromatic polycarboxylic promotor. These conditions are adjusted in order to produce a hydrogen contact step wherein the hydrogen and promotor are present in a concentration sufiicient to effect production of lower boiling hydrocarbons and are adjusted in order to maximize the yield of lower boiling hydrocarbons from the heavy hydrocarbon fraction.

In carrying out the oxidation step, an oxidant is utilized such as oxygen (including air and activated oxygen) ozone, organic peroxides, organic hydroperoxides and organic peracids, optionally in the presence of a metal catalyst.

The concentration of oxidants is usually dependent upon the increase in oxygen content which is to be obtained during the oxidation step such as oxygen content increases as set forth above. In general air rates of from about 500 to 20,000 preferably from about 2,000 to 12,000 standard cubic feet (s.c.f.) per barrel of hydrocarbon charge stock are utilized. In the case of ozone, organic peroxides, organic hydroperoxides and organic peracids a concentration of oxidant generally within the range of from about 1.0 to about 10 moles of oxidant per mole of oxygen incorporated into the hydrocarbon material is utilized more preferably from about 1.5 to about 4 moles of oxidant. It is preferred to use an excess of both air and other types of oxidants above that needed to incorporate the actual number of moles of oxygen (representing the oxygen increase) into the hydrocarbon charge stock, preferably from about 20 to about 500% excess oxidant. The preferred oxidant which is utilized in carrying out the process of this invention and which produces random oxidation of the hydrocarbon charge stock is oxygen. When a catalyst is employed, it is preferred to use a catalyst concentration varying from about 0.0001 to about wt. percent based upon the weight of the heavy hydrocarbon fraction and still more preferably from about 0.10 to about 10 wt. percent, the catalyst being used at a concentration which is sufficient to promote the effectiveness of the oxidant. The temperature utilized in carrying out the oxidation step can vary over a wide range and in general a temperature of from about 28 F. to about 450 F. is utilized, depending upon the oxidant, although higher and lower temperatures can be utilized. In general the oxidant contacts the heavy hydrocarbon fractions for a time generally within the range of from about minutes to about 24 hours preferably from about one half hour to about hours. The time that is utilized of necessity depends upon the nature of the heavy hydro carbon fraction and the type of oxidant. In the case of a gas, the time can vary over a wide range depending upon the particular amount of gas such as oxygen or ozone which is passed into the reaction mixture, that is the rate of introduction of oxygen or ozone into the heavy hydrocarbon fraction. In general for the oxidation step utilizing oxygen, a temperature within the range of from about 150 F. to about 650 F., preferably within the range of from about 200 F. to about 400 F. is utilized. When ozone is utilized as the oxidant, a low temperature such as from 20 F. to about 125 F. is utilized. The quantity of oxidant utilized in the oxidation step can be obtained during the time utilized for the oxidation step. The process of this invention in general is carried out at atmospheric pressure although pressures above atmospheric for example up to about 100 atmospheres can be utilized.

The organic oxidants include by way of example hydrocarbon peroxides, hydroperoxides and hydrocarbon peracids wherein the hydrocarbon radicals in general contain from about 1 to about 30 carbon atoms per linkage. With respect to the hydrocarbon peroxides and hydrocarbon hydroperoxides, it is particularly preferred that such hydrocarbon radical contain from 4 to 30 carbon atoms per peroxide linkage and more particularly from 4 to 16 carbon atoms per peroxide linkage. With respect to the hydrocarbon peracids the hydrocarbon radical which is attached to the carbonyl carbon in general contains from 1 to about 12 carbon atoms more preferably from about 1 to about 8 carbon atoms. It is intended that the term organic peracid includes by way of definition performic acid.

In addition it is contemplated within the scope of this invention that the organic oxidants can be prepared in situ, that is the peroxide, hydroperoxide or peracid can be generated in the heavy hydrocarbon fraction and such organic oxidant is contemplated for use within the scope of this invention.

Typical examples of hydrocarbon radicals are alkyl such as methyl, ethyl, butyl, t-butyl, 3-methyl-1-pentyl, n-octyl and those aliphatic radicals which represent the hydrocarbon portion of a middle distillate or kerosene, cycloalkyl radicals such as cyclopentyl, alkylated cycloalkyl radicals such as mono and polymethylcyclopentyl radicals, aryl and cycloalkyl substituted alkyl radicals such as phenyl and alkylphenyl substituted alkyl radicals examples of which are benzyl, methylbenzyl, caprylbenzyl, phenylethyl, phenylpropyl, naphthylmethyl, naphthylethyl, aryl radicals such as phenyl, and napthyl, alkaryl radicals such as xylyl, alkylphenyl, and ethylphenyl.

Typical examples of oxidants are hydroxyheptyl peroxide, cyclohexanoneperoxide, t-butyl peracetate, di-tbutyl diperphthalate, t-butyl perbenzoate, methylethylketone peroxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butylperoxide, p-menthane hydroperoxide, pinane hydroperoxide, 2,5-dimethylhexane-2,S-dihydroperoxide and cumene hydroperoxide, organic peracids, such as performic acid, peracetic acid, trichloroperacetic acid, perbenzoic acid and perphthalic acid.

The catalyst which can be utilized to promote the oxidation of the heavy hydrocarbon fraction varies with the particular oxidant. The particularly preferred catalysts for use in air oxidation of the hydrocarbon fraction are potassium sulfate promoted vanadium oxide on alumina, vanadium oxide plus molybdenum oxide on alumina promoted with magnesium oxide, aluminum vanadate, vanadium oxide such as when prepared by hydrolysis of butyl vanadate with water in the presence of a porous catalyst carrier, vanadium oxide, silver oxide and stannic oxide on pumice, tin vanadate on asbestos. Examples of catalysts which can be utilized with ozone, organic peroxides, organic hydroperoxides and organic peracids are metals such as titanium, zirconium, vanadium, tantalum, chromium, molybdenum and tungsten, the most preferred catalyst metals being titanium, vanadium, and molybdenum. These catalyst can be incorporated into the oxidation system by any means known to those skilled in the art, and can be either a homogeneous or heterogeneous catalyst system. The catalyst can be incorporated by a variety of means and by the use of a variety of carriers. The particular catalyst carrier which is utilized is not critical with respect to the practice of this invention and can be for example, a support medium or an anion (including complex formation) which is attached to the metal (e.g. a ligand). Illustrative ligands include halides, organic acids, alcoholates, mercaptides, sulfonates and phenolates. These metals may also be bound by a variety of complexing agents including acetonylacetonates, amines, ammonia, carbon monoxide and olefins, amongst others. The metals may also be introduced in the form of organometallics including ferrocene type structures. The various ligands illustrated above which are utilized solely as carriers to incorporate the metal into the process system, in general have an organic radical attached to a functional group such as the oxygen atom of carbonyloxy group of the acid, the oxygen of the alcohol, the sulfur of the mercaptan, the

of the sulfonate, the oxygen of the phenolic compound and the nitrogen of the amines. The organic radical attached to the aforedescribed functional groups can be defined as a hydrocarbon radical and in general can contain from 1 to about 30 carbon atoms. Typical examples of hydrocarbon radicals are set forth above.

The metals contained on the heterogeneous catalyst can include individual or combinations of metals. These metals can be suspended on a suitable material, for example alumina, silica (or combinations of both) as well as activated clays or carbon, amongst others. The modes of contacting whereby the catalytic effect may be achieved may include slurry-bed reactions or continuous contacting over a stationary phase in a trickle-tube reactor.

The heavy hydrocarbon fraction which has been subjected to an oxidation step is contacted with hydrogen in the presence of an aromatic polycarboxylic compound. In general a temperature of from 550 F. to about 900 F. preferably from about 650 F. to about 775 F.; pressures of from about 500 to about 3,000 p.s.i.g. preferably 1,000 to about 2,000 p.s.i.g.; liquid hourly space velocities of from about 0.1 to about 10 preferably from about 0.5 to about 2.5 volumes of feed per volume of contactor void space per hour; and hydrogen rates of from about 2,000 to about 20,000 preferably from about 4,000 to about 12,000 standard cubic feet (s.c.f.) per barrel of feed are utilized in the hydrogen contact step.

Typical examples of aromatic polycarboxylic compounds are represented by the structural formula:

each R is a hydrocarbon radical, a is an integer having a value of from 2 to 4 and b is an integer having the value of from to 4 provided that the sum of a+b is not greater than 6. The particularly preferred aromatic carboxylic acid and/or anhydride producing compounds are those compounds represented by the above formula wherein R is selected from alkyl having from 1 to about 6 carbon atoms, hydrogen and when two groups represented together form In a still more preferred embodiment of this invention, b

is from zero to two, more preferably 11 is zero and R is selected from hydrogen and when two groups represented by t C-OR together form When b is greater than zero it is preferred that R have from about 1 to about 8 carbon atoms, more preferably from 1 to about 3 carbon atoms. Typical examples of aromatic nucleus are benzene, naphthalene, anthracene, biphenyl and terphenyl. It is preferred that the aromatic nucleus is selected from benzene, naphthalene and b1- phenyl, more preferably that the aromatic nucleus is benzene.

Typical examples of hydrocarbon radicals representing R and R are set forth above. In addition, R and R are defined as hydrocarbon radicals which are non-intefering with respect to the promoting activity of the aromatic polycarobxylic compound. By non-interfering is meant the substituents representing R and R do not completely nullify the activity of the promoter during the hydrogen process step.

Typical examples of aromatic polycarboxylic acid, anhydride producing compounds are phthalic anhydride, m-phthalic meta acid, terphthalic acid, pyromellitic anhydride, trimellitic anhydride, pyromellitic acid, trimellitic acid, dimethyl terphthalate, diisopropyl terphthalate, dibenzyl terphthalate and dimethylophthalate.

A wide variety of heavy hydrocarbon fractions and/or distillates may be treated, or made suitable for further processing, through the utilization of the method encompassed by the present invention. Such heavy hydrocarbon fractions include full boiling range crude oils, topped or reduced crude oils, atmospheric distillates, vacuum tower bottoms, visbreaker bottoms product, heavy cycle stocks from thermal or catalytically-cracked charge stocks, etc. The present method is particularly well adaptable to the treating of crude oils and topped or reduced crude oils containing large quantities of asphaltenic material, and is especially advantageous when applied to the treating of atmospheric or vacuum tower bottoms e.g. especially 550 F. or higher atmospheric reduced crude oils.

A particularly preferred heavy hydrocarbon fraction which can be utilized in the process of this invention are the deasphalted atmospheric and vacuum tower residues which have been topped to temperatures of at least 550 F. at atmospheric pressure.

The present invention can be carried out in batch, continuous or semi-continuous operating cycles, and in one or more actual or theoretical stages, employing contacting and separation equipment such as has heretofore been employed in hydrocracking of petroleum stocks. In addition a multi-stage mode of operation that is a repeating of the process several times can be utilized in carrying out the process of this invention.

The process of this invention can be better appreciated by the following non-limiting examples.

EXAMPLE 1 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 R, an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight phthalic anhydride. The temperature is increased to 750 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 2 To a pressure reactor equipped with gas addition means is added 1000 grams of a San Ardo crude oil. The temperature is increased to 600 F. and air introduced into the reactor until a pressure of 600 p.s.i.g. is obtained. The air pressure is maintained for a period of 3 hours after which the temperature is reduced to ambient temperature. The oxidized oil is then charged to a high pressure autoclave and the temperature is increased to 725 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for 2 hours after which the temperature is reduced to ambient temperature.

EXAMPLE 3 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 F., an air pressure of 50 p.s.i.g., a liquid hourly spaced velocity of 1.0, and an air rate of 6000 s.c .f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight trimellitic anhydride. The temperature is increased to 750 F and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

7 EXAMPLE 4 To a reactor is continuously charged a San Ardo crude alumina catalyst. A temperature of 35 R, an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight pyromellitic anhydride. The temperature is increased to 750 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 5 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 F an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight dimethyl terphthalate. The temperature is increased to 750 F. and maintained under a hydrogen pressure of 1.500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 6 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 R, an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight terphthalic acid. The temperature is increased to 750 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 7 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 R, an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by dibenzyl terphthalate. The temperature is increased to 75 0 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 8 To a reactor is continuously charged a San Ardo crude oil over a potassium sulfate promoted vanadium oxide on alumina catalyst. A temperature of 350 R, an air pressure of 50 p.s.i.g., a liquid hourly space velocity of 1.0, and an air rate of 6000 s.c.f. per bbl. is maintained. The oxidized oil is reduced to ambient temperature and charged to a high pressure autoclave together with 1% by weight dicyclohexyl terphthalate. The temperature is increased to 750 F. and maintained under a hydrogen pressure of 1500 p.s.i.g. for a period of 2 hours. The temperature is then reduced to ambient temperature.

EXAMPLE 9 To a high pressure autoclave is charged 1000 grams of San Ardo crude and the temperature is increased to 750 F. under a hydrogen pressure of 1500 p.s.i.g. The temperature and hydrogen pressure is maintained for a period of 2 hours after which the temperature is reduced to ambient temperature.

EXAMPLE 10 Example 9 is repeated using San Ardo crude oil to which has been added 1% by weight phthalic anhydride.

8 In the table is listed the yield of different fractions on a weight percent basis which were obtained after fractional distillation of hydrocarbon materials which were subjected to various treatments.

TABLE San Ardo crude charge Product from Example N0- 1 2 9 10 stock Product analysis yield,

wt. percent:

04-400 F 7. 7 11. 2 16. 2 1. 3 400 F650 F. 25. 6 27. 4 2G. 1 15. 6 650 F-850 F 20. 8 24. 6 22.0 20. 6 850 F 27. 9 45. 8 36. 8 35. 7 G2. 5 850 F. plus conversion 55. 5 26. 7 41. 0 43. 0 Sulfur, \vt. percent 1.15 1.56 1. 28 1. 30 2 30 Nitrogen, wt. percent 0.73 0. 89 0. 03 0.87 1. 08

The results of the table demonstrate the outstanding effectiveness of the process of this invention for increasing the yield of lower boiling hydrocarbons. More particularly the combination of oxidation step plus hydrogen contact step in the presence of aromatic polycarboxylic compound gave yields of 850-]- F. conversion of 55.5% whereas the air oxidized step alone gave only a 26.7% conversion. In addition the percent conversion for the hydrogenation contact step alone in the absence of the aromatic polycarboxylic compound was 41 wt. percent whereas the presence of the aromatic polycarboxylic compound under the same conditions gave a percent conversion of 43.0 wt. percent. These results both as to the use of an oxidation step separately and to the use of the hydrogen contact step separately when compared to the percent conversion of 55.5 wt. percent utilizing the process of this invention demonstrates the outstanding performance of the process for increasing the yield of low boiling hydrocarbons.

While this invention has been described with respect to various specific examples and embodiments it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

'We claim:

1. A process which comprises contacting a heavy hydrocarbon fraction with an oxidizing amount of an oxidant optionally in the presence of an oxidation promoting catalyst, contacting said oxidized heavy hydrocarbon fraction with hydrogen in the presence of a promoting amount of an added aromatic polycarboxylic compound and recovering an increased proportion of lower boiling hydrocarbons than that present in the heavy hydrocarbon fraction.

2. A process of claim 1 wherein the aromatic polycarboxylic compound is represented by the structural formula 0 l Ar hydrocarbon radical having from about 1 to about 12 carbon atoms and any two groups represented by which are attached to adjacent carbon atoms on Ar can together form each R is a hydrocarbon radical, a is an integer having a value of from 2 to 4, and b is an integer having a value of from 0 to 4 provided that the sum of a+b is not greater than 6.

3. A process of claim 2 wherein b has a value of 0, R is selected from the group consisting of alkyl having from 1 to about 6 carbon atoms, hydrogen and when two groups represented by H ll -COR together form C\ II o 4. A process of claim 3 wherein R is selected from the group consisting of hydrogen and when two groups representing 5. A process of claim 4 wherein the aromatic polycarboxylic compound is phthalic anhydride.

6. A process of claim 1 wherein the process is carried out in the presence of a catalyst selected from the group consisting of vanadium, silver and molybdenum and the oxidant is oxygen.

7. A process of claim 2 wherein the process is carried out in the presence of catalyst selected from the group consisting of vanadium, silver and molybdenum and the oxidant is oxygen.

8. A process of claim 1 wherein the heavy hydrocarbon fraction is a reduced crude oil.

9. A process of claim 2 wherein the heavy hydrocarbon fraction is a reduced crude oil.

10. A process of claim 6 wherein the heavy hydrocarbon fraction is a reduced crude oil.

References Cited UNITED STATES PATENTS HERBERT LEVINE, Primary Examiner US. Cl. X.R. 208-4, 107, 108 

